JP6907970B2 - Hybrid vehicle - Google Patents

Description

The present invention relates to a hybrid vehicle.

Conventionally, there is known a hybrid vehicle including an internal combustion engine and an electric motor, which has an electric supercharger that supercharges the intake gas supplied to the internal combustion engine (for example, Patent Documents 1 and 2).

Of these, the hybrid vehicle described in Patent Document 1 includes a regenerative generator that converts the kinetic energy of the vehicle or internal combustion engine into electric power and recovers it. When the charge rate (SOC) of the battery exceeds a predetermined value while the regenerative generator is operating, the regenerative power supplied by the regenerative generator is consumed by supplying power to the electric supercharger. I am trying to do it. In particular, in the hybrid vehicle described in Patent Document 1, when the power that can be consumed by the electric supercharger is calculated based on the pressure ratio before and after the electric supercharger and the calculated power that can be consumed is low, for example, The amount of power supplied to devices other than the electric supercharger is increased, and the amount of power generated by the regenerative generator is reduced by operating the mechanical brake.

Japanese Unexamined Patent Publication No. 2017-136974 Japanese Unexamined Patent Publication No. 2008-23209

By the way, when the capacity of the electric motor of the hybrid vehicle is relatively small and the required torque for the hybrid vehicle is larger than a certain level, the required torque of the hybrid vehicle cannot be output only by the electric motor. Therefore, in such a hybrid vehicle, when the required torque is larger than a certain level, the required torque is satisfied by driving the internal combustion engine.

In such a hybrid vehicle, when the required torque for the hybrid vehicle is larger than a certain level, for example, when the charge rate of the battery becomes high and it is necessary to release the electric power charged in the battery, the electric supercharger is used. Not only by supplying electric power, but also by supplying electric power to the electric motor, the electric power charged in the battery can be reduced. At this time, if the amount of electric power supplied to the electric supercharger is increased, the supercharging pressure is increased, so that the pumping loss in the internal combustion engine is reduced. Therefore, the thermal efficiency in the internal combustion engine is increased, and as a result, the fuel consumption in the internal combustion engine can be reduced. On the other hand, when the amount of electric power supplied to the motor is increased, the output torque of the internal combustion engine required to satisfy the required torque for the hybrid vehicle is reduced, and as a result, the fuel consumption in the internal combustion engine can be reduced. Therefore, in order to reduce the fuel consumption in the internal combustion engine as much as possible at this time, it is necessary to appropriately distribute the electric power from the battery to the electric supercharger and the electric motor.

However, in Patent Document 1, when it is necessary to increase the amount of electric power supplied from the battery, the electric power is basically supplied to the electric supercharger. Then, when the regenerative power cannot be completely consumed by the electric supercharger, power is supplied to a device other than the electric supercharger. It is not always possible to efficiently reduce the fuel consumption in the internal combustion engine simply by increasing the supply of electric power to the electric supercharger in this way. Therefore, there is room for improvement in terms of reducing fuel consumption in hybrid vehicles.

The present invention has been made in view of the above problems, and an object of the present invention is to appropriately control an electric motor and an electric supercharger to reduce fuel consumption when the amount of electric power supplied from a battery should be increased. The purpose is to provide a hybrid vehicle that can be efficiently reduced.

The present invention has been made to solve the above problems, and the gist thereof is as follows.

(1) A hybrid vehicle equipped with an internal combustion engine and an electric motor as a power source, which is connected to an electric supercharger that supercharges the intake gas supplied to the internal combustion engine and the electric motor and the electric supercharger. A battery that supplies electric power to the electric motor and the electric supercharger, and a control device that controls the internal combustion engine, the electric motor, and the electric supercharger are provided, and the control device is based on the charge rate of the battery. When it is determined whether or not it is time to increase the total power supply amount from the battery to the motor and the electric supercharger, and it is determined that it is time to increase the total power supply amount from the battery. In the power supply promotion control, the control device performs power supply promotion control for increasing the total power supply amount from the battery, and the control device in the internal combustion engine with respect to the increase in the total power supply amount from the battery in the power supply promotion control. A hybrid vehicle that controls the amount of power supplied to the motor and the amount of power supplied to the electric supercharger so that the fuel saving rate, which is the rate of decrease in fuel consumption, is maximized.

(2) In the power supply promotion control, the control device has at least an operating point determined by the power supply amount to the electric supercharger, the power supply amount to the electric motor, and the fuel supply amount to the internal combustion engine. The fuel saving rate when the first operation of maintaining the output torque of the vehicle is performed while increasing the amount of power supplied to the electric motor and reducing the amount of fuel supplied to the internal combustion engine as compared with the case of being at the operating point. The output torque of the internal combustion engine is maintained while increasing the amount of power supplied to the electric supercharger and decreasing the amount of fuel supplied to the internal combustion engine as compared with the case where the operating point is at the certain operating point. The fuel saving rate when the second operation is performed is calculated, and the point at which the operating point reaches when the operation with the larger calculated fuel saving rate is executed is calculated as the updated operating point. The control is executed only once or a plurality of times, and the power supply amount to the electric motor, the power supply amount to the electric supercharger, and the fuel supply to the internal combustion engine at the finally calculated update operation point. The hybrid vehicle according to (1) above, wherein the electric motor, the electric supercharger, and the internal combustion engine are controlled so as to be in quantity.

(3) In the power supply promotion control, the renewal operation calculation control is repeatedly executed until the total power supply amount from the battery at the renewal operation point exceeds the limit value, and one before the finally calculated renewal operation point. The internal combustion engine, the electric motor, and the electric supercharger are controlled so as to be the amount of electric power supplied to the electric supercharger, the amount of electric power supplied to the electric motor, and the amount of fuel supplied to the internal combustion engine at the operating point of. The hybrid vehicle according to (2) above.

(4) When the control device determines that it is not time to increase the total power supply amount from the battery, the internal combustion engine is stopped when the required torque to the hybrid vehicle is equal to or less than a predetermined value. Even when it is determined that the hybrid vehicle is driven only by the electric motor and the control device increases the total power supply amount from the battery, the required torque to the hybrid vehicle is the predetermined value. The hybrid vehicle according to any one of (1) to (3) above, wherein when the following is the case, the internal combustion engine is stopped and the hybrid vehicle is driven only by the electric motor.

According to the present invention, a hybrid vehicle capable of appropriately controlling an electric motor and an electric supercharger to sufficiently reduce fuel consumption in an internal combustion engine when the amount of electric power supplied from the battery to the outside should be increased. Is provided.

FIG. 1 is a diagram schematically showing a configuration of a hybrid vehicle according to the first embodiment. FIG. 2 is a diagram schematically showing a configuration of an internal combustion engine mounted on a hybrid vehicle. FIG. 3 is a diagram showing the relationship between the required torque and the operating state. FIG. 4 is a diagram showing the engine torque that maximizes fuel efficiency for each engine rotation speed. FIG. 5 is a diagram showing an operating state of the hybrid vehicle when the required torque for the hybrid vehicle is medium. FIG. 6 is a diagram similar to FIG. 5 showing an operating state of the hybrid vehicle when the required torque for the hybrid vehicle is medium. FIG. 7 is a diagram similar to FIG. 5 showing an operating state of the hybrid vehicle when the required torque for the hybrid vehicle is medium. FIG. 8 is a diagram showing the relationship between the engine output, the degree of supercharging by the electric supercharger, and the fuel consumption of the internal combustion engine. FIG. 9 is a diagram similar to FIG. 8 showing the relationship between the output of the internal combustion engine and the fuel consumption. FIG. 10 is a diagram showing the relationship between the engine output, the degree of supercharging by the electric supercharger, and the fuel consumption of the internal combustion engine. FIG. 11 is a diagram similar to FIG. 10 showing the relationship between the engine output, the degree of supercharging by the electric supercharger, and the fuel consumption of the internal combustion engine. FIG. 12 is a diagram similar to FIGS. 10 and 11 showing the relationship between the engine output, the degree of supercharging by the electric supercharger, and the fuel consumption of the internal combustion engine. FIG. 13 is a flowchart showing a control routine of power supply promotion control that increases the total power supply amount from the battery. FIG. 14 is a flowchart showing a control routine of the update operation point calculation control performed during the power supply promotion control shown in FIG. FIG. 15 shows a map used to calculate the fuel consumption of an internal combustion engine at each operating point. FIG. 16 shows a map used to calculate the fuel consumption of an internal combustion engine at each operating point. FIG. 17 shows a map used to calculate the fuel consumption of the internal combustion engine at each operating point. FIG. 18 shows a map used to calculate the fuel economy of an internal combustion engine at each operating point.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, similar components are given the same reference numbers.

<Vehicle configuration>
FIG. 1 is a diagram schematically showing the configuration of the hybrid vehicle 1 according to the first embodiment. As shown in FIG. 1, the vehicle 1 includes an internal combustion engine 10, a first motor generator 12, a second motor generator 14, and a power split mechanism 16. In addition, the vehicle 1 includes a power control unit (PCU) 18 electrically connected to the first motor generator 12 and the second motor generator 14, a battery 20 electrically connected to the PCU 18, and electronic control. It includes a unit (ECU) 30.

The internal combustion engine 10 is a prime mover that burns fuel such as gasoline or light oil inside the engine to convert the thermal energy of the combustion gas into mechanical energy. The output of the internal combustion engine 10 is controlled by adjusting the amount of fuel and air supplied to the internal combustion engine 10. The output shaft (crankshaft) of the internal combustion engine 10 is mechanically connected to the power split mechanism 16, and the power generated by the internal combustion engine 10 is input to the power split mechanism 16.

The input / output shafts of the first motor generator 12 are mechanically connected to the power split mechanism 16 and electrically connected to the PCU 18. When the electric power is supplied from the PCU 18, the first motor generator 12 is driven by the electric power and outputs the electric power to the power dividing mechanism 16. Therefore, at this time, the first motor generator 12 functions as a motor.

On the other hand, when power is input to the first motor generator 12 from the power split mechanism 16, the first motor generator 12 is driven by the power to generate electric power. The generated electric power is supplied to the battery 20 via the PCU 18, and the battery 20 is charged. Therefore, at this time, the first motor generator 12 functions as a generator. The first motor generator 12 may be a generator that does not function as a motor.

The input / output shafts of the second motor generator 14 are mechanically connected to the power split mechanism 16 and electrically connected to the PCU 18. When the electric power is supplied from the PCU 18, the second motor generator 14 is driven by the electric power and outputs the electric power to the power dividing mechanism 16. Therefore, at this time, the second motor generator 14 functions as a motor.

On the other hand, when power is input to the second motor generator 14 from the power split mechanism 16, the second motor generator 14 is driven by the power to generate electric power. The generated electric power is supplied to the battery 20 via the PCU 18, and the battery 20 is charged. Therefore, at this time, the second motor generator 14 functions as a generator. The second motor generator 14 may be a motor that does not function as a generator.

The power split mechanism 16 is mechanically connected to the internal combustion engine 10, the first motor generator 12, and the second motor generator 14. In addition, the power split mechanism 16 is connected to the drive shaft 22, and the drive shaft 22 is connected to the wheels 26 via the differential gear 24. In particular, in the present embodiment, the power split mechanism 16 includes a planetary gear mechanism. In this planetary gear mechanism, for example, the sun gear is connected to the input / output shaft of the first electric generator 12, the planetary gear is connected to the output shaft of the internal combustion engine 10, and the ring gear is connected to the input / output shaft of the second electric generator 14. Is connected to.

The power split mechanism 16 is input to the power split mechanism 16 from any one of the internal combustion engine 10, the first motor generator 12, the second motor generator 14, and the drive shaft 22 connected to the power split mechanism 16. The power is configured to be able to be output to at least one of these components. Therefore, for example, when power is input from the internal combustion engine 10 to the power split mechanism 16, this power is output to at least one of the first motor generator 12, the second motor generator 14, and the drive shaft 22. Will be done. Similarly, when power is input from the first motor generator 12 to the power split mechanism 16, this power is output to at least one of the internal combustion engine 10, the second motor generator 14, and the drive shaft 22. NS. In addition, when power is input from the second motor generator 14 to the power split mechanism 16, this power is output to at least one of the internal combustion engine 10, the first motor generator 12, and the drive shaft 22. NS.

The PCU 18 includes an inverter, a DCDC converter, and the like, and is electrically connected to the first motor generator 12, the second motor generator 14, and the battery 20. The PCU 18 controls the first motor generator 12, the second motor generator 14, and the battery 20, converts the electric power supplied from the battery 20 to the motor generators 12, 14, and the motor generators 12, 14 Converts the power supplied from the battery 20 to the battery 20.

The battery 20 is electrically connected to the PCU 18 and stores electricity. When the first motor generator 12 or the second motor generator 14 is driven by the power input from the power split mechanism 16, the battery 20 is charged via the PCU 18. On the other hand, when the first motor generator 12 or the second motor generator 14 outputs power to the power split mechanism 16, electric power is transmitted from the battery 20 to the first motor generator 12 or the second motor generator 14 via the PCU 18. Be supplied.

The ECU 30 is composed of a digital computer and includes a RAM (random access memory), a ROM (read-only memory), a CPU (microprocessor), and an input port and an output port connected to each other via a bidirectional bus. The input port and output port of the ECU 30 are connected to various actuators of the internal combustion engine 10, various sensors, a PCU 18, a battery 20, and the like. The output signals of the various sensors of the internal combustion engine 10, the PCU 18, and the battery 20 are input to the ECU 30. In addition, the ECU 30 outputs control signals to various actuators of the internal combustion engine 10, the PCU 18, and the battery 20. Therefore, the various actuators, PCU18, and battery 20 of the internal combustion engine 10 are controlled by the ECU 30.

In the vehicle 1 configured in this way, when a part or all of the power obtained by the internal combustion engine 10 is input to the first motor generator 12 or the second motor generator 14, the first motor generator 12 or the second Power can be generated by the motor generator 14. The electric power obtained by such power generation is charged to the battery 20 via the PCU 18 or supplied to the motor generator 12 of the first motor generator 12 and the second motor generator 14 which is not generating power. Or Therefore, the vehicle 1 is configured so that the electric power generated by the output of the internal combustion engine 10 can be charged to the battery 20. Further, when a part or all of the power obtained by the internal combustion engine 10 is input to the drive shaft 22, the wheels 26 can be rotated by this power.

Further, the vehicle 1 is configured so that the first motor generator 12 or the second motor generator 14 can be driven by the electric power supplied from the battery 20. The power obtained by driving the first motor generator 12 or the second motor generator 14 can be input to the internal combustion engine 10. Therefore, the internal combustion engine 10 that is stopped can be started by such power. Further, when the power obtained by driving the first motor generator 12 or the second motor generator 14 is input to the drive shaft 22, the wheels 26 can be rotated by this power.

In the present embodiment, the vehicle 1 includes two motor generators 12 and 14. However, the vehicle 1 does not necessarily have to have two motor generators 12 and 14, and may have only one motor generator.

<Composition of internal combustion engine>
FIG. 2 is a diagram schematically showing a configuration of an internal combustion engine 10 mounted on a hybrid vehicle 1. As shown in FIG. 2, the internal combustion engine 10 includes an engine main body 40, a fuel supply device 43, an intake system 50, and an exhaust system 60. The engine body 40 includes a plurality of cylinders 41, and a combustion chamber in which the air-fuel mixture burns is formed in each cylinder 41. Each cylinder 41 may be provided with a spark plug (not shown) for igniting the air-fuel mixture in the combustion chamber of each cylinder 41.

The fuel supply device 43 includes a fuel injection valve 44, a delivery pipe 45, a fuel supply pipe 46, a fuel pump 47, and a fuel tank 48. The fuel injection valve 44 is arranged in the engine body 40 so as to directly inject fuel into the combustion chamber of each cylinder 41. The fuel injection valve 44 is connected to the fuel tank 48 via the delivery pipe 45 and the fuel supply pipe 46. A fuel pump 47 for pumping fuel in the fuel tank 48 is arranged in the fuel supply pipe 46. The fuel pumped by the fuel pump 47 is supplied to the delivery pipe 45 via the fuel supply pipe 46, and is directly injected from the fuel injection valve 44 into the combustion chamber as the fuel injection valve 44 is opened.

The intake system 50 includes an intake manifold 51, an intake pipe 52, an air cleaner 53, a compressor 70c of an exhaust turbocharger 70, an electric supercharger 54, an intercooler 55, and a throttle valve 56. Each cylinder 41 communicates with the intake manifold 51 via the intake port, and the intake manifold 51 communicates with the air cleaner 53 via the intake pipe 52.

The intake pipe 52 is provided with an electric supercharger 54 that compresses and discharges the intake air flowing through the intake pipe 52. The electric supercharger 54 is connected to the battery 20 and is driven by the electric power supplied from the battery 20. The electric supercharger 54 can increase the pressure of the intake air as the supplied electric power increases.

The intake pipe 52 is further provided with a compressor 70c of the exhaust turbocharger 70 and an intercooler 55 for cooling the air compressed by the compressor 70c. The intercooler 55 is arranged on the downstream side of the compressor 70c in the flow direction of the intake air. The throttle valve 56 is arranged in the intake pipe 52 between the intercooler 55 and the intake manifold 51. The throttle valve 56 can be rotated to change the opening area of the intake passage.

The exhaust system 60 includes an exhaust manifold 61, an exhaust pipe 62, a turbine 70t of an exhaust turbocharger 70, and an exhaust aftertreatment device 63. Each cylinder 41 communicates with the exhaust manifold 61 via an exhaust port, and the exhaust manifold 61 communicates with the exhaust pipe 62. The exhaust pipe 62 is provided with a turbine 70t of the exhaust turbocharger 70. The turbine 70t is rotationally driven by the energy of the exhaust gas. The compressor 70c of the exhaust turbocharger 70 and the turbine 70t are connected by a rotating shaft, and when the turbine 70t is rotationally driven, the compressor 70c rotates accordingly, and thus the intake air is compressed. Further, the exhaust pipe 62 is provided with an exhaust aftertreatment device 63 on the downstream side in the exhaust flow direction of the turbine 70t. The exhaust aftertreatment device 63 is a device for purifying exhaust gas and then discharging it into the outside air, and includes various exhaust purification catalysts for purifying harmful substances, a filter for collecting harmful substances, and the like.

The ECU 30 is connected to various sensors. For example, the intake pipe 52 is provided with an air flow meter 75 that detects the flow rate of the intake air flowing in the intake pipe 52, and the ECU 30 is connected to the air flow meter 75. Further, the hybrid vehicle 1 includes a load sensor 77 whose output current changes according to the output of the accelerator pedal 76, and this load sensor 77 is also connected to the ECU 30.

On the other hand, the ECU 30 is connected to various actuators of the internal combustion engine. In the example shown in FIG. 2, the ECU 30 is connected to the fuel injection valve 44, the fuel pump 47, the electric supercharger 54, and the throttle valve 56, and controls these actuators.

<Basic vehicle output control>
Next, the basic operation control of the hybrid vehicle 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing the relationship between the required torque and the operating state, and FIG. 4 is a diagram showing the engine torque (hereinafter, referred to as “optimal fuel efficiency torque”) that maximizes fuel efficiency for each engine rotation speed.

As shown in FIG. 3, in the present embodiment, the driving force to the hybrid vehicle 1 is applied according to the required torque calculated based on the output of the load sensor 77, that is, according to the required torque to the hybrid vehicle 1. The supplier changes. In the example shown in FIG. 3, when the required torque for the hybrid vehicle 1 is low and less than Te1, the hybrid vehicle 1 is driven only by the motor generators 12 and 14. Therefore, when the required torque is less than Te1, the internal combustion engine 10 is stopped.

Therefore, when the required torque to the hybrid vehicle is equal to or less than the predetermined value Te1, it is determined that it is time to increase the total power supply amount from the battery 20 as described later, but it is not the time to increase it. Also in this case, the internal combustion engine 10 is stopped and the hybrid vehicle 1 is driven only by the motor generators 12 and 14.

On the other hand, in the hybrid vehicle 1 of the present embodiment, the capacities of the motor generators 12 and 14 are not so large. Therefore, when the required torque for the hybrid vehicle 1 is in the middle of Te1 or more, the required torque cannot be satisfied only by the motor generators 12 and 14. Therefore, when the required torque for the hybrid vehicle 1 is Te1 or more, the internal combustion engine 10 is activated, and thus the hybrid vehicle 1 is driven by the internal combustion engine 10.

Here, as shown in FIG. 4, the optimum fuel consumption torque is relatively high at each engine speed. Therefore, when the required torque for the hybrid vehicle 1 is a medium torque between Te1 and Te2, if the internal combustion engine 10 is operated so that the output torque of the internal combustion engine 10 becomes the optimum torque for fuel consumption, the hybrid vehicle The output torque of the internal combustion engine 10 is larger than the required torque of 1. Therefore, when the required torque for the hybrid vehicle 1 is a torque between Te1 and Te2, the internal combustion engine 10 is operated so that its output torque becomes the optimum torque for fuel consumption, and the surplus torque causes the motor generator. 12 and 14 are driven to generate electricity. As a result, the internal combustion engine 10 can be operated in a fuel-efficient state, and the excess torque can be converted into electric power and stored.

FIG. 5 is a diagram showing an operating state of the hybrid vehicle 1 when the required torque for the hybrid vehicle 1 is medium. In particular, A in the figure shows a case where the internal combustion engine 10 is operated so that the output torque of the internal combustion engine 10 becomes equal to the required torque of the hybrid vehicle 1 (when the operation is performed at the operating point A). On the other hand, A'in the figure indicates a case where the output torque of the internal combustion engine 10 is higher than the required torque of the hybrid vehicle 1 and therefore power generation is performed by the surplus torque (when the operation is performed at the operating point A'). Shown. The operating point indicates the operating state of the hybrid vehicle 1 determined by at least the amount of power supplied to the electric supercharger 54, the amount of power supplied to the motor generators 12 and 14, and the amount of fuel supplied to the internal combustion engine 10. ..

As shown in FIG. 5A, when the operation is performed at the operating point A', the output torque of the internal combustion engine 10 is higher than when the operation is performed at the operating point A. In particular, at the operating point A', the internal combustion engine 10 is operated so that the output torque of the internal combustion engine becomes the optimum fuel consumption torque.

Further, as shown in FIG. 5B, at the operating point A, the required torque of the hybrid vehicle 1 and the output torque of the internal combustion engine 10 are equal to each other. On the other hand, at the operating point A', the torque obtained by subtracting the torque (power generation torque) used for power generation in the motor generators 12 and 14 from the output torque of the internal combustion engine 10 matches the required torque of the hybrid vehicle 1.

In addition, the fuel supply amount in the internal combustion engine 10 (fuel supply amount in each cycle) is basically proportional to the output torque of the internal combustion engine 10. Therefore, as shown in FIG. 5C, the fuel supply amount at the operating point A'is larger than the fuel supply amount at the operating point A. In addition, at the operating point A, the hybrid vehicle 1 is not driven by the motor generators 12 and 14, and supercharging is not performed by the electric supercharger 54. Therefore, at the operating point A, the amount of power supplied to the motor generators 12 and 14 and the electric supercharger 54 is almost zero. On the other hand, at the operating point A', since the motor generators 12 and 14 generate power, the power supply amount becomes a negative value.

Further, when the required torque for the hybrid vehicle 1 is high and is Te2 or more, the hybrid vehicle 1 is driven by the motor generators 12 and 14 in addition to the internal combustion engine 10. In this case, the internal combustion engine 10 is operated so that its output torque is as close to the optimum fuel consumption torque as possible, and the motor generators 12 and 14 generate an output torque corresponding to the difference between the required torque and the optimum fuel consumption torque. Driven like. Further, when the required torque becomes higher and the required torque cannot be satisfied even if the output torques of the motor generators 12 and 14 are maximized, the internal combustion engine 10 is operated so as to exceed the optimum fuel consumption torque and have a high output torque. NS.

<Issues when requesting SOC reduction>
By the way, when the SOC (State of Charge), which is the ratio of the current charge capacity to the full charge capacity of the battery 20, is low, the motor generators 12 and 14 generate power, and the power obtained by the power generation is used as the battery 20. Can be charged to. However, since the amount of electric power that can be charged to the battery 20 is limited, when the SOC is high, the battery 20 cannot be charged any more, and therefore the motor generators 12 and 14 cannot generate electric power.

Here, as described above, when the required torque for the hybrid vehicle 1 is in the middle of Te1 or more and less than Te2, the motor generators 12 and 14 basically generate power. However, when the SOC is high, the motor generators 12 and 14 cannot generate electricity. Therefore, when the required torque for the hybrid vehicle 1 is medium, it is necessary to operate the internal combustion engine 10 at the operating point A instead of the operating point A'where the fuel efficiency is optimal.

Here, if the hybrid vehicle 1 travels on a long downhill with a high SOC, the hybrid vehicle 1 cannot generate regenerative power generation, and the hybrid vehicle 1 must be decelerated by the brake system. Therefore, in such a case, the regenerative energy becomes heat and is wasted.

In order to suppress such a situation, it is conceivable to reduce the SOC of the battery 20 in advance before the hybrid vehicle 1 invades a long downhill. By reducing the SOC of the battery 20 in advance in this way, when the hybrid vehicle 1 is traveling downhill, the battery 20 can be charged by the regenerative energy, whereby the hybrid vehicle 1 can be charged. Fuel economy can be improved.

The fuel efficiency can be improved in this way even when the torque required for the hybrid vehicle 1 is medium when the SOC of the battery 20 is reduced in advance. That is, even when the required torque for the hybrid vehicle 1 is medium, in order to reduce the SOC, the motor generators 12 and 14 generate the torque, and then the internal combustion engine 10 has the optimum fuel consumption torque. It is necessary to operate with a lower torque than. Therefore, when the SOC of the battery 20 is reduced in advance, the fuel consumption of the internal combustion engine 10 deteriorates. However, if power can be generated by the regenerative energy when traveling downhill, it is possible to charge the internal combustion engine 10 by the regenerative energy more than the deterioration of the fuel consumption.

Further, in addition to the case where the hybrid vehicle 1 is expected to travel downhill from now on, it may be necessary to reduce the SOC of the battery 20 in a state where the required torque for the hybrid vehicle 1 is medium. .. When it is necessary to reduce the SOC of the battery 20 in this way, that is, when it is required to increase the total power supply amount from the battery 20 to the motor generators 12 and 14 and the electric supercharger 54. In order to satisfy this requirement, the overall fuel consumption of the hybrid vehicle 1 will be deteriorated at least temporarily. Therefore, from the viewpoint of suppressing the deterioration of the fuel consumption of the hybrid vehicle 1, in such a case, it is necessary to minimize the deterioration of the overall fuel consumption of the hybrid vehicle 1.

<SOC reduction method>
By the way, when the required torque for the hybrid vehicle 1 is Te1 or more and the required torque cannot be satisfied unless the internal combustion engine 10 is operated, two main methods can be considered as a method for reducing the SOC of the battery 20.

The first method is to maintain the output torque of the hybrid vehicle 1 while increasing the amount of electric power supplied to the motor generators 12 and 14 and reducing the amount of fuel supplied to the internal combustion engine 10 (hereinafter,). , Such an operation is called "first operation"). Hereinafter, the first method will be specifically described with reference to FIG.

FIG. 6 is a diagram similar to FIG. 5 showing an operating state of the hybrid vehicle 1 when the required torque for the hybrid vehicle 1 is medium. In particular, the operating point A in the figure shows a case where the internal combustion engine 10 is operated so that the output torque of the internal combustion engine 10 becomes equal to the required torque of the hybrid vehicle 1 (when the operation is performed at the operating point A). This is the same as A in FIG. On the other hand, at the operating point B in the figure, the output torque of the internal combustion engine 10 is lower than the required torque of the hybrid vehicle 1 with respect to the operating point A, and the insufficient torque is supplemented by the output torques of the motor generators 12 and 14. (When the operation is performed at the operation point B).

As shown in FIG. 6A, when the operation is performed at the operating point B, the output torque of the internal combustion engine 10 is lower than when the operation is performed at the operating point A. Further, as shown in FIG. 6B, at the operating point A, the required torque of the hybrid vehicle 1 and the output torque of the internal combustion engine 10 are equal to each other. On the other hand, at the operating point B, the total torque of the output torque of the internal combustion engine 10 and the output torques of the motor generators 12 and 14 matches the required torque of the hybrid vehicle 1.

In addition, since the output torque of the internal combustion engine 10 at the operating point B is lower than the output torque of the internal combustion engine 10 at the operating point A, as shown in FIG. 6C, the fuel supply amount at the operating point B is the operation. It is less than the fuel supply at point A. Further, at the operating point A, the motor generators 12 and 14 and the electric supercharger 54 are not driven, whereas at the operating point B, the motor generators 12 and 14 drive the hybrid vehicle 1. Therefore, the amount of power supplied at the operating point B is larger than that at the operating point A.

The second method is a method of maintaining the output torque of the internal combustion engine 10 while increasing the amount of electric power supplied to the electric supercharger 54 and reducing the amount of fuel supplied by the internal combustion engine 10 (hereinafter, such a method). The operation is called "second operation"). As a result, the output torque of the hybrid vehicle 1 is maintained even in this method. Hereinafter, the second method will be specifically described with reference to FIG. 7.

FIG. 7 is a diagram similar to FIG. 5 showing an operating state of the hybrid vehicle 1 when the required torque for the hybrid vehicle 1 is medium. In particular, the operating point A in the figure is the same as A in FIGS. 5 and 6. On the other hand, the operating point C in the figure increases the power supply amount to the electric supercharger 54 and decreases the fuel supply amount of the internal combustion engine 10 with respect to the operating point A, resulting in the output of the internal combustion engine 10. The case where the torque is maintained (when the operation is performed at the operation point C) is shown.

As shown in FIG. 7A, the output torque when the operation is performed at the operation point C is equal to the output torque when the operation is performed at the operation point A. Further, as shown in FIG. 7B, the required torque of the hybrid vehicle 1 and the output torque of the internal combustion engine 10 are the same both when the operation is performed at the operation point A and when the operation is performed at the operation point C. Become equal.

In addition, at the operating point C, the intake gas supplied to the internal combustion engine 10 by supplying electric power to the electric supercharger 54 is supercharged. Since the supercharging is performed by the electric supercharger 54 in this way, the pumping loss is reduced, so that the thermal efficiency in the internal combustion engine is increased. Therefore, the output torque of the internal combustion engine 10 can be maintained even if the fuel supply amount to the internal combustion engine 10 is reduced from the operating point A. Therefore, at the operating point C, the fuel supply amount is smaller than that at the operating point A, but the electric power supply amount is larger.

As described above, at the operating point B, the fuel supply amount is smaller than that at the operating point A, but the total power supply amount from the battery 20 is larger. Similarly, at the operating point C, the fuel supply amount is smaller than that at the operating point A, but the total power supply amount from the battery 20 is larger. Then, assuming that the ratio of the decrease in the fuel supply amount to the increase in the total power supply amount from the battery is the fuel saving rate, the fuel saving rate at the operating point B and the operating point C is the operating point A and other engine operating states. It changes according to. Therefore, depending on the operating point A and other engine operating conditions, the operating point B has a higher fuel saving rate than the operating point A, and conversely, depending on the operating point A and other engine operating conditions, the operating point A Has a higher fuel saving rate than the operating point B.

<Search for operating points with high fuel saving rate>
Therefore, in the present embodiment, the motor turbocharger 54 is searched for the target operating point that maximizes the fuel saving rate, and the hybrid vehicle 1 is operated at the operating point that maximizes the fuel saving rate. The motor generators 12 and 14 and the internal combustion engine 10 are controlled. In the following, a method of searching for a target operating point that maximizes the fuel saving rate will be described with reference to FIGS. 8 and 9.

FIG. 8 is a diagram showing the relationship between the engine output, the degree of supercharging by the electric supercharger 54, and the fuel consumption of the internal combustion engine 10. In FIG. 8, a plurality of solid lines show the relationship when the amount of power supplied to the electric supercharger 54 is different. Here, consider a case where the operating point of the hybrid vehicle 1 is at the operating point A when it is necessary to reduce the SOC of the battery 20.

In this case, when the first operation described above is performed, the amount of power supplied to the motor generators 12 and 14 is increased, and thus the output of the motor generators 12 and 14 is increased. At this time, the amount of power supplied to the electric supercharger 54 does not change. Assuming that the required output of the hybrid vehicle 1 has not changed, it is necessary to reduce the output of the internal combustion engine 10 by the amount of increase in the output of the motor generators 12 and 14. When the output of the internal combustion engine 10 is reduced, the output torque of the internal combustion engine 10 deviates from the optimum fuel consumption torque, so that the fuel consumption of the internal combustion engine 10 deteriorates (the amount of fuel supplied per unit output increases). As a result, when the first operation is performed, the operating point of the hybrid vehicle 1 shifts from A to B in FIG. The fuel saving rate when the operating point shifts from A to B is calculated by dividing the decrease in the fuel supply amount to the internal combustion engine 10 by the increase in the power supply amount to the motor generators 12 and 14. Will be done.

On the other hand, when the second operation described above is performed, the amount of electric power supplied to the electric supercharger 54 is increased, and thus the supercharging pressure in the internal combustion engine 10 is increased. When the boost pressure rises, the pumping loss is reduced and the thermal efficiency is raised, so that the fuel supply amount to the internal combustion engine 10 can be reduced while maintaining the output of the internal combustion engine 10, and thus the fuel consumption of the internal combustion engine 10 is improved. do. As a result, when the second operation is performed, the operating point of the hybrid vehicle 1 shifts from A to C in FIG. Further, the fuel saving rate when the operating point shifts from A to C is calculated by dividing the decrease in the fuel supply amount to the internal combustion engine 10 by the increase in the power supply amount to the electric supercharger 54. NS.

Then, the fuel saving rate when the first operation is performed and the fuel saving rate when the second operation is performed are compared, and the operating point reached after executing the operation having the larger fuel saving rate is the updated operating point. (Such control is called updated operation point calculation control). After that, the operating point reached when the first operation is performed with reference to this updated operating point, the fuel saving rate associated with this first operation, and the fuel saving rate when the second operation is performed with reference to this updated operating point are reached. The operating point and the fuel saving rate associated with this second operation are calculated. Then, these fuel saving rates are compared again, and the operating point reached after executing the operation having the larger fuel saving rate is calculated as the next updated operating point, and then the same operation is repeated.

FIG. 9 is a diagram similar to FIG. 8 showing the relationship between the output of the internal combustion engine 10 and the fuel consumption. In the example shown in FIG. 9, as a result of comparing the case where the first operation is performed from the operating point A (when the operating point B is reached) and the case where the second operation is performed (when the operating point C is reached), the first operation is performed. The fuel saving rate is larger when one operation is performed. Therefore, the operating point B is calculated as the updated operating point from the operating point A.

In the example shown in FIG. 9, the result of comparing the case where the first operation is performed from the operation point B (when the operation point D is reached) and the case where the second operation is performed (when the operation point E is reached) are then compared. , The fuel saving rate is larger when the second operation is performed. Therefore, the operating point E is calculated as the updated operating point from the operating point B. In the example shown in FIG. 9, in the same manner, the operating point G is calculated as the updated operating point from the operating point E, and the operating point I is calculated as the updated operating point from the operating point G.

Here, when the first operation or the second operation is performed from a certain operating point, at the operating point reached as a result of executing the operation, the battery 20 to the motor generators 12, 14 and the electric supercharger are compared with the operating point before the operation. The total amount of power supplied to the feeder 54 increases. Therefore, as the number of times the operating point is repeatedly updated by repeatedly performing the first operation or the second operation, the total power supply amount gradually increases. Then, a limit value is set in advance for this total power supply amount. This limit value is set to, for example, a power supply amount such that the discharge current from the battery 20 reaches the current limit value.

Therefore, if the renewal operation point calculation control is repeatedly performed and the operation point is renewed repeatedly, the total power supply amount at the renewal operation point calculated will eventually exceed the limit value. Therefore, in the present embodiment, when the total power supply amount at the finally calculated update operation point exceeds the limit value, the operation point calculated immediately before the finally calculated update operation point Is specified as the target driving point.

In the example shown in FIG. 9, the total power supply amount at the operating point G is equal to or less than the limit value, but the total power supply amount at the operating point I exceeds the limit value. Therefore, the operating point G calculated immediately before the finally calculated updated operating point I is specified as the target operating point. Then, the electric power supply amount to the electric supercharger 54, the power supply amount to the motor generators 12 and 14, and the fuel supply amount to the internal combustion engine 10 at the target operating point specified in this way are obtained. The turbocharger 54, the motor generators 12, 14 and the internal combustion engine 10 are controlled.

When the target operating point is searched for in this way, the finally calculated target operating point is the operating point having the highest fuel saving rate among the operating points having the same total power supply amount. Therefore, in the present embodiment, it can be said that the electric power supply amount to the motor generators 12 and 14 and the electric power supply amount to the electric supercharger 54 are controlled so as to maximize the fuel saving rate. Then, according to the present embodiment, when the amount of electric power supplied from the battery 20 to the outside should be increased, the fuel in the hybrid vehicle 1 is fueled by appropriately controlling the motor generators 12 and 14 and the electric supercharger 54. The consumption rate can be reduced efficiently.

In the above embodiment, the target operation point is the operation point calculated immediately before the update operation point finally calculated so that the total power supply amount exceeds the limit value. However, the target value of the total power supply amount may be set in advance, and the update operation point finally calculated so that the total power supply amount exceeds the target value may be set as the target operation point.

<Correction according to operating conditions>
By the way, the relationship between the engine output shown in FIG. 8, the degree of supercharging by the electric supercharger, and the fuel consumption of the internal combustion engine 10 is not the same in all operating states, but changes depending on the operating state of the internal combustion engine 10. do. Specifically, these relationships change depending on, for example, the flow rate of the intake gas in the intake passage composed of the intake manifold 51 and the intake pipe 52, the pumping loss, the equivalence, the friction in the internal combustion engine 10, and the like. ..

FIG. 10 is a diagram showing the relationship between the engine output, the degree of supercharging by the electric supercharger 54, and the fuel consumption of the internal combustion engine 10. The broken line in the figure indicates when the flow rate of the intake gas is low, and the solid line in the figure indicates when the flow rate of the intake gas is high.

As can be seen from FIG. 10, when the flow rate of the intake gas is large, the change in the fuel consumption of the internal combustion engine 10 when the degree of supercharging by the electric supercharger 54 is changed is smaller than when the flow rate of the intake gas is small. .. This is because when the flow rate of the intake gas is large, the pressure of the intake gas does not easily increase even if supercharging is performed by the electric supercharger 54.

When the flow rate of the intake gas increases, the fuel saving rate is calculated based on the relationship shown by the broken line in FIG. As described above, when the flow rate of the intake gas increases, the change in the fuel consumption of the internal combustion engine 10 is small even if the amount of power supplied to the electric supercharger 54 changes and the degree of supercharging by the electric supercharger 54 changes. Therefore, increasing the amount of power supplied to the electric supercharger 54 is not so effective. Therefore, at the operating point finally calculated based on the above search, when the flow rate of the intake gas increases, the power supply amount to the motor generators 12 and 14 is relative to the power supply amount to the motor supercharger 54. The ratio increases.

Further, the relationship when the equivalence is reduced is the same as the relationship when the flow rate of the intake gas is reduced. Therefore, the relationship between the engine output, the degree of supercharging by the electric supercharger 54, and the fuel consumption of the internal combustion engine 10 is the same as the relationship shown by the broken line in FIG. 10 even when the equivalence is lowered. That is, when the equivalence is lowered, the change in the fuel consumption of the internal combustion engine 10 when the supercharging degree by the electric supercharger 54 is changed is smaller than when the isochoric is large. The reason for this is considered to be as follows. That is, when the isochoricity decreases, the exhaust energy increases, and as a result, supercharging is performed by the exhaust turbocharger 70. Therefore, the supercharging effect due to the use of the electric supercharger 54 is reduced. Therefore, at the operating point finally calculated based on the above search, when the equivalence decreases, the amount of power supplied to the motor generators 12 and 14 increases, as in the case where the flow rate of the intake gas increases. The ratio to the amount of electric power supplied to the electric supercharger 54 increases.

FIG. 11 is a diagram similar to FIG. 10 showing the relationship between the engine output, the degree of supercharging by the electric supercharger 54, and the fuel consumption of the internal combustion engine 10. The broken line in the figure indicates when the pumping loss is large, and the solid line in the figure indicates when the pumping loss is small.

As can be seen from FIG. 11, when the pumping loss is large, the change in the fuel consumption of the internal combustion engine 10 when the degree of supercharging by the electric supercharger 54 is changed is larger than when the pumping loss is small. This is because the larger the pumping loss when supercharging by the electric supercharger 54 is not performed, the more the thermal efficiency in the internal combustion engine 10 can be improved by supercharging by the electric supercharger 54. ..

When the pumping loss becomes large, the fuel saving rate is calculated based on the relationship shown by the broken line in FIG. As described above, when the pumping loss becomes large, the amount of electric power supplied to the electric supercharger 54 changes, and when the degree of supercharging by the electric supercharger 54 changes, the fuel consumption of the internal combustion engine 10 changes significantly. It is effective to increase the amount of power supplied to the supercharger 54. Therefore, at the operating point finally calculated based on the above search, when the pumping loss becomes large, the ratio of the electric power supply amount to the motor generators 12 and 14 to the electric power supply amount to the electric supercharger 54 becomes. It becomes smaller.

FIG. 12 is a diagram similar to FIGS. 10 and 11 showing the relationship between the engine output, the degree of supercharging by the electric supercharger 54, and the fuel consumption of the internal combustion engine 10. The broken line in the figure indicates when the friction in the internal combustion engine 10 is large, and the solid line in the figure indicates when the friction is small.

As can be seen from FIG. 12, when the friction is large, the fuel consumption of the internal combustion engine 10 is worse than when the friction is small. Therefore, the relationship between the engine output shown in FIG. 12 and the fuel consumption of the internal combustion engine 10 shifts upward as a whole as the friction increases.

However, the ratio of the change in the fuel consumption of the internal combustion engine 10 to the change in the degree of supercharging by the electric supercharger 54 and the ratio of the change in the fuel consumption of the internal combustion engine 10 to the change in the engine output are basically the same even if the friction changes. It does not change. Therefore, at the operating point finally calculated based on the above search, the ratio of the amount of power supplied to the motor generators 12 and 14 to the amount of power supplied to the motor turbocharger 54 even if the friction changes. Does not change.

<Specific control>
Next, the control of the hybrid vehicle 1 will be described with reference to FIGS. 13 and 14. FIG. 13 is a flowchart showing a control routine of power supply promotion control that increases the total power supply amount from the battery 20. The illustrated control routine is executed at regular time intervals.

First, in step S11, it is determined whether or not the calculation flag is set to 0. The calculation flag is a flag that is set to 1 when the update operation point is being calculated, and is set to 0 at other times. When the update operation point has not been calculated and the calculation flag is set to 0, the process proceeds to step S12. In step S12, it is determined whether or not the execution condition of the power supply promotion control for increasing the total power supply is satisfied, that is, whether or not it is time to increase the total power supply amount from the battery 20.

The execution condition of the power supply promotion control is satisfied, for example, when the hybrid vehicle 1 travels downhill with a high SOC and its fuel consumption is expected to deteriorate. Specifically, first, the SOC of the battery 20 is detected by the PCU 18. In addition, depending on the navigation system (not shown) connected to the ECU 30, whether or not there is a downhill in the traveling route of the hybrid vehicle 1 in the near future, and if there is a downhill, its length, slope, etc. Is detected. Then, when the detected SOC is equal to or higher than the reference threshold value, it is determined that the execution condition of the power supply promotion control is satisfied. The reference threshold is changed based on, for example, the length of the downhill, the slope of the downhill, and the like.

Further, the execution condition of the electric charge supply promotion control is not satisfied when the required torque for the hybrid vehicle 1 is less than the predetermined value Te1. This is because when the required torque for the hybrid vehicle 1 is less than the predetermined value Te1, the internal combustion engine 10 may be stopped and the hybrid vehicle 1 may be driven only by the motor generators 12 and 14.

If it is determined in step S12 that the execution condition of the power supply promotion control is not satisfied, the control routine is terminated. On the other hand, if it is determined that the execution condition of the power supply promotion control is satisfied, the process proceeds to step S13. In step S13, the calculation flag is set to 1. Next, in step S14, the current operating point is set as the initial operating point. Specifically, the current operating point is calculated based on each output signal of the ECU 30 and the like.

Next, in step S15, the update operation point calculation control shown in FIG. 14 is executed, and the update operation point is calculated. Next, in step S16, it is determined whether or not the total power supply amount to the motor generators 12 and 14 and the electric supercharger 54 at the renewal operation point is equal to or higher than a predetermined limit value. Here, the limit value is set to a power supply amount such that the discharge current from the battery 20 becomes large and reaches the current limit value. If it is determined in step S16 that the total power supply amount is less than the limit value, the control routine is terminated.

In the next control routine, it is determined in step S11 that the calculation flag is not set to 0, and the process proceeds to step S15. In step S15, a further updated operation point is calculated by the update operation point calculation control with reference to the update operation point calculated in the previous control routine. Next, in step S16, it is determined whether or not the total power supply amount is equal to or more than a predetermined limit value, and if it is less than the limit value, the control routine is terminated.

When the control routine is repeatedly executed in this way and the update operation point calculation control is repeatedly executed, the total power supply amount gradually increases and eventually reaches the limit value or more. In the control routine in which the total power supply amount is equal to or higher than the limit value, it is determined in step S16 that the total power supply amount is equal to or higher than the predetermined limit value, and the process proceeds to step S17.

In step S17, the update operation point before being calculated by the update operation point calculation control in the current control routine (the operation point input to the update operation point calculation control in step S15 in this control routine), that is, one. The previous update operating point is set as the target operating point. Then, the amount of power supplied to the motor generators 12 and 14, the amount of power supplied to the electric supercharger 54, the amount of target fuel supplied to the internal combustion engine 10, and the like are controlled so that the operating point becomes this target operating point. Will be done.

Next, in step S18, it is determined whether or not the current SOC of the battery 20 is equal to or less than the target SOCtg. The current SOC is calculated, for example, by PCU18. Further, the target SOCtg is determined based on the free capacity required for the battery 20, for example, the target SOCtg is set small so that the longer the slope in the traveling path of the hybrid vehicle 1, the larger the free capacity of the battery 20. If it is determined in step S18 that the SOC is greater than the target SOCtg, the control routine is terminated. Therefore, in the next control routine, the update operation point is calculated again by the update operation point calculation control.

On the other hand, if it is determined in step S18 that the SOC is equal to or less than the target SOCtg, the process proceeds to step S19. In step S19, the calculation flag is set to 0 and the control routine is terminated.

FIG. 14 is a flowchart showing a control routine of the update operation point calculation control performed during the power supply promotion control shown in FIG. The illustrated control routine is executed each time the control routine of FIG. 13 reaches step S15.

First, in step S21, the operating point is acquired. In the updated operation point calculation control for the first time after the calculation flag is set to 1 in the control routine of FIG. 13, the operation point acquired at this time is the initial operation point set in step S14 of FIG. On the other hand, since the calculation flag is set to 1, in the second and subsequent update operation point calculation controls, the operation point acquired at this time is the update operation point calculated in step S15 in the previous control routine of the power supply promotion control. Is.

Next, in step S22, the fuel saving rate FR1 when the first operation is performed is calculated. Here, the procedure for calculating the fuel saving rate FR1 when the first operation is performed is as follows: the operating point before the first operation is the operating point A in FIGS. 6 and 8, and the operating point after the first operation is FIG. And the case where it is the operation point B of FIG. 8 will be described as an example.

First, the change ΔQ of the amount of power supplied to the motor generators 12 and 14 at the operating points A and B is set. The change ΔQ of the power supply amount is set to a predetermined constant value. Next, the engine output EP _A at the operating point A and the fuel consumption FC _{A at the} operating point A are calculated. The engine output EP _A at the operating point A is calculated by multiplying the current engine rotation speed of the internal combustion engine 10 by the fuel supply amount (that is, engine torque) to the internal combustion engine 10 for each cycle at the operating point A. Will be done. Further, the fuel consumption FC at each operating point is calculated by, for example, the following method.

First, the basic fuel consumption FCb of the internal combustion engine 10 is calculated using the map as shown in FIG. 15 based on the engine output and the amount of pressure increase due to supercharging in the electric supercharger 54. The amount of pressure increase due to supercharging in the electric supercharger 54 is calculated based on the amount of power supplied to the electric supercharger 54, engine output, and the like. The map showing the relationship between the engine load, the amount of pressure rise, and the basic fuel consumption FCb as shown in FIG. 15 is calculated in advance experimentally or by calculation based on the relationship as shown in FIG. 8, and is calculated in advance by the ROM of the ECU 30. It is saved in. The map shown in FIG. 15 may be, for example, a multidimensional map in which the engine rotation speed is further added as an argument.

Next, the first fuel consumption correction value FC1 is calculated using the map as shown in FIG. 16 based on the engine output and the flow rate of the intake gas. The flow rate of the intake gas is calculated based on, for example, the output of the air flow meter 75 provided in the intake passage of the internal combustion engine 10. The map showing the relationship between the engine load, the flow rate of the intake gas, and the first fuel consumption correction value FC1 as shown in FIG. 16 is calculated in advance experimentally or by calculation based on the relationship as shown in FIG. , Stored in the ROM of the ECU 30. The map shown in FIG. 16 may be, for example, a multidimensional map in which the engine rotation speed and the amount of pressure increase due to supercharging in the electric supercharger 54 are further added as arguments.

In addition, the second fuel consumption correction value FC2 is calculated using the map as shown in FIG. 17 based on the engine output and the pumping loss. The pumping loss is calculated based on, for example, the in-cylinder pressure during the intake stroke and the exhaust stroke detected by a sensor (not shown) that detects the in-cylinder pressure of the internal combustion engine 10. The map showing the relationship between the engine load, the pumping loss, and the second fuel consumption correction value FC2 as shown in FIG. 17 is calculated in advance experimentally or by calculation based on the relationship as shown in FIG. 11, and the ECU 30 It is saved in the ROM of. The map shown in FIG. 17 may be, for example, a multidimensional map in which the engine rotation speed and the amount of pressure increase due to supercharging in the electric supercharger 54 are further added as arguments.

Further, the third fuel consumption correction value FC3 is calculated using the map as shown in FIG. 18 based on the engine output and the equivalence. The equivalence is calculated based on, for example, a transition of the in-cylinder pressure in the compression stroke from the intake stroke detected by a sensor (not shown) that detects the in-cylinder pressure of the internal combustion engine 10. The map showing the relationship between the engine load, the equivalence and the third fuel consumption correction value FC3 as shown in FIG. 18 is calculated in advance experimentally or by calculation based on the relationship as shown in FIG. It is saved in the ROM of the ECU 30. The map shown in FIG. 18 may be, for example, a multidimensional map in which the engine rotation speed and the amount of pressure increase due to supercharging in the electric supercharger 54 are further added as arguments.

Then, the fuel consumption FC of the internal combustion engine 10 is calculated by adding the first fuel consumption correction value FC1, the second fuel consumption correction value FC2, and the third fuel consumption correction value FC3 to the basic fuel consumption FCb calculated in this way ( FC = FCb + FC1 + FC2 + FC3).

Such methods fuel consumption F _A at operating point A by multiplying the engine output EP _A at operating point A on the fuel consumption FC _A at operating point A, which is calculated by is calculated (F _A = FC _A × EP _A ). Similarly, the fuel consumption F _B is calculated at the operating point B by multiplying the engine output EP _B at the operating point B on the fuel consumption FC _B at the operating point _{B (F B = FC B ×} EP B). _{Then, by subtracting the fuel consumption F B} at the operating point B from the fuel consumption F _{A at the} operating point A, the decrease ΔF of the fuel consumption due to the shift of the operating point from A to B is calculated (ΔF =). F _A − F _B ). Then, by dividing the decrease in fuel consumption ΔF by the change in power supply ΔQ, the fuel saving rate when the operating point shifts from A to B, that is, the fuel saving rate FR1 when the first operation is performed, is obtained. It is calculated (FR1 = ΔF / ΔQ).

Next, in step S23, the fuel saving rate FR2 when the second operation is performed is calculated. Here, in the procedure for calculating the fuel saving rate FR2 when the second operation is performed, the operating point before the second operation is the operating point A in FIGS. 7 and 8, and the operating point after the second operation is FIG. 7. And the case where it is the operation point C of FIG. 8 will be described as an example.

First, the change ΔQ of the amount of power supplied to the electric supercharger at the operating point A and the operating point C is set. The change ΔQ of the power supply amount is set to a predetermined constant value. Next, the amount of decrease in fuel consumption ΔF due to the shift of the operating point from A to C is calculated in the same manner as in step S22. Then, by dividing the decrease amount ΔF of the fuel consumption amount by the depreciation amount ΔQ of the electric charge supply amount, the fuel saving rate when the operating point shifts from A to C, that is, the fuel saving rate FR2 when the second operation is performed is obtained. It is calculated (FR2 = ΔF / ΔQ).

Next, in step S24, it is determined whether or not the fuel saving rate FR1 in the first operation calculated in step S22 is equal to or higher than the fuel saving rate FR2 in the second operation calculated in step S23. If it is determined in step S24 that FR1 is FR2 or higher, the process proceeds to step S24. In step S25, the operating point reached after performing the first operation from the operating point acquired in step S21 is calculated as the update operating point, and the control routine is terminated.

On the other hand, if it is determined in step S24 that FR1 is less than FR2, the process proceeds to step S26. In step S26, the operating point reached after performing the second operation from the operating point acquired in step S21 is calculated as the update operating point, and the control routine is terminated.

<Modification example>
In the above embodiment, the target operating point is calculated by searching on the ECU 30. However, it is not always necessary to calculate the target operating point by searching. For example, the target operating point is determined based on a multidimensional map based on engine output, engine speed, intake gas flow rate, pumping loss, and equivalence. It may be calculated. In this case as well, the target operating point is calculated so that the fuel saving rate from the current operating point is maximized.

However, if the target operating point is calculated based on a map with a large number of parameters as arguments without calculating the target operating point by searching, the number of man-hours required for creating the map becomes enormous and the data is saved in the ROM of the ECU 30. The amount of data to be output becomes huge.

1 Hybrid vehicle 10 Internal combustion engine 12 1st motor generator 14 2nd motor generator 18 PCU
20 battery 30 ECU
44 Fuel injection valve 54 Electric supercharger

Claims (3)

A hybrid vehicle equipped with an internal combustion engine and an electric motor as a power source.
An electric supercharger that supercharges the intake gas supplied to the internal combustion engine, a battery that is connected to the motor and the electric supercharger and supplies power to the motor and the electric supercharger, and the internal combustion engine. The engine, the motor, and a control device for controlling the electric supercharger are provided.
The control device determines whether or not it is time to increase the total power supply amount from the battery to the motor and the electric supercharger based on the charge rate of the battery, and determines whether or not it is time to increase the total power supply from the battery. When it is determined that it is time to increase the supply amount, power supply promotion control for increasing the total power supply amount from the battery is performed.
In the power supply promotion control, the control device maximizes the fuel saving rate, which is the ratio of the decrease in fuel consumption in the internal combustion engine to the increase in total power supply from the battery. By controlling the amount of power supplied to the electric supercharger and the amount of power supplied to the electric supercharger ,
In the power supply promotion control, the control device has an operating point determined by at least the amount of power supplied to the electric supercharger, the amount of power supplied to the electric motor, and the amount of fuel supplied to the internal combustion engine. The fuel saving rate when the first operation of maintaining the output torque of the hybrid vehicle is performed while increasing the amount of power supplied to the electric motor and decreasing the amount of fuel supplied to the internal combustion engine as compared with a certain time, and the above-mentioned A second that maintains the output torque of the internal combustion engine while increasing the amount of power supplied to the electric supercharger and decreasing the amount of fuel supplied to the internal combustion engine as compared with the case where the operating point is at the certain operating point. Update operation point calculation control that calculates the fuel saving rate when the operation is performed and calculates the point where the operation point reaches as the update operation point when the operation with the larger calculated fuel saving rate is executed. The amount of power supplied to the electric motor, the amount of power supplied to the electric supercharger, and the amount of fuel supplied to the internal combustion engine at the finally calculated update operation point are executed only once or repeatedly. A hybrid vehicle that controls the electric motor, the electric supercharger, and the internal combustion engine so as to be. In the power supply promotion control, the renewal operation calculation control is repeatedly executed until the total power supply amount from the battery at the renewal operation point exceeds the limit value, and the operation point immediately before the finally calculated renewal operation point is executed. The internal combustion engine, the electric motor, and the electric supercharger are controlled so as to be the amount of electric power supplied to the electric supercharger, the amount of electric power supplied to the electric motor, and the amount of fuel supplied to the internal combustion engine. Item 2. The hybrid vehicle according to item 1. Wherein the controller, when the required torque to the person the hybrid vehicle is less than the predetermined value, the irrespective of the whether the time to increase the total amount of electric power supplied from the battery, while stopping the internal combustion engine wherein only by the electric motor drive the said hybrid vehicle, the hybrid vehicle according to claim 1 or 2.

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